Far-UVC light: A tool to control the spread of airborne-mediated microbial
nature.com
nature.com
>However, the widespread use of germicidal ultraviolet light in public settings has been very limited because conventional UVC light sources are a human health hazard, being both carcinogenic and cataractogenic
conventional UVC is generated by mercury light bulbs and are carcinogenic and cataractogenic
BUT about 10 years ago, it became practical to use frequency doubling in LEDs to generate light really close to the mercury light - the LEDs are not carcinogenic and cataractogenic. When you read about UVC effects, you should check what type of light source they are using (mercury vs LED)
Also, it is the advancements in silicon manufacturing that has made it cheaper to make new and different LEDs - such as these "far-UVCs". It is pretty legit!
There is "a lot" of research demonstrating effectiveness of "conventional UVC", but not a lot on "far-UVC". One of the limitations on both is the shadow effect... got to go. I'll elaborate if there is interest
Yes please
https://theblindhorse.com/the-blind-horse-becomes-first-rest...
You can easily check that there is no true pitch black shadow open place in a room, this is the whole idea behind "global illumination rendering".
And are you sure about this? When visible light gets reflected by a wall it doesn't seem to change wavelength significantly (color basically remains the same).
https://wonderopolis.org/wonder/why-does-a-black-light-make-...
I would say that the re-emitted light has a “longer” wavelength. Fluorescence always produces a longer wavelength. UVC becomes UVB, UVB becomes UVA, UVA becomes blue, etc. Though different materials increase the wavelengths to different degrees. That is why “black lights” can produce different fluorescent colors.
And did you ever use a blacklight in a dark room? Many things are shining. For example teeth. So smilling could get 220nm to a dangerous zone and kill the one that is smiled at? … hehe little joke.
I'm imagining a washing machine full of masks (COVID concentrators), beaming UV-C light at them as they spin around.
Would that mitigate some of the shadow effect, because they're in motion?
I also seriously doubt that the LEDs are based on silicon since indirect bandgap semiconductors make horribly inefficient light sources. Also the bandgap of silicon is somewhere in the near infrared.
Frequency doubling requires exteremely high intensites that are usually only reached by focussed laser beams. I don't see how one could use it in a LED.
What makes the LED light not dangerous that way? As far as I understand, what makes UVC effective is also what makes it dangerous.
UV LEDs can be manufactured to produce a very narrow spectrum centered on 220nm. So with an LED the total amount of UV produced is much less and doesn't include problematic frequencies that cause eye and tissue damage. Supposedly, I don't work in this space.
Note most UV LED's aren't suitable for sterilization. If it comes in a plastic case and costs 30 cents, it's certainly not.
Does anyone know of any manufacturer? I don't think they exist yet?
Unfortunately, current state-of-the-art UV LEDs do not produce enough power at the 220nm wavelength to be commercially viable.
The current state-of-the-art uses KrCl excimer lamps to generate this light, with optical filters to eliminate spillage in the undesired frequencies (> 230nm).
> KrCl excimer lamps
Maybe the intensity is less…. :). Or the range of uv is more specific.
Lol! Yeah, UV light from mercury gives you cancer, but the same electromagnetic radiation from LEDs is totally harmless! LEDs are green, haven’t you heard?
A single wavelength emission from a far-UVC led source is therefore safer.
I don’t know why it hasn’t been productive since the start of the pandemic.
I would naively think that exposing the forced airflow to the treatment would be both simpler and safer than installing a system into every room with people.
Keep in mind the filters have to be able to filter the dead pathogens anyway (usually same size) or else you are breathing them, which isn't great either. Better than live ones for sure, but not great.
As for UV, you can add it to either residential or commercial easily (some preschools and schools I've visited added them in the past year). It doesn't make sense to install in every room, as you say.
On ozone, see https://www.epa.gov/coronavirus/air-cleaners-hvac-filters-an... and the section on ozone.
It's a screwball idea, but I wonder if there might actually be health benefits to reliably killing pathogens without filtering them out of the air - sort of like low-dose inactivated-agent vaccines for everything you would have actually been exposed to otherwise.
If you look at a graph of the blocking efficiency of an N95 filter vs particle size, that graph is a curvy "V" shape, with the bottom of that "V" being at 0.3 microns.
The bigger issue is not whether you can get filters to do it, it's whether your system was built for the pressure drop you'd need to do it.
IE UV's advantage is that it doesn't really drop pressure (but does require some dwell time), not that you can't filter air well enough.
Having the UV in the room with the people means it treats every breath immediately.
Most places with lots of people also have very high acph - often 20-30 air changes per hour.
One we actually installed in our hospital is a replacement for the regular fluorescent lights you see in every building. It's a direct swap out so pretty easy for any maintenance crew to complete. Instead of directing the UV light into the room, it simply has a duct inside with a fan that directs air to pass by powerful UV lights. The UV light is contained to a small box within the unit and the people around never are exposed. The only drawback is the fan noise, but in hospitals, the background sound is already pretty high. I believe you can schedule the fan to stop overnight. Otherwise it basically continuously circulates the air in the room, always passing over a UV source to kill pathogens that might be in the air.
EDIT - just to clarify, you swap out the whole box, not just the bulb. Like this (http://2.bp.blogspot.com/-etoHnNVcOnw/Tu0xY9sDwCI/AAAAAAAAA3...) but usually in a drop ceiling.
The positive effects are a) vitamin d production b) germicide
The negative effects are c) lower energy efficiency in the visible spectrum (watt per visible light produced) d) negative effect on the eye e) carciogenic
For indoor keeping of reptiles UVB light seems to be needed [2] As far as i've read, for indoor planting, UV light seems to beneficial as well, for example it increases the production of THC [3]
Why should we, as humans, be different ?
[1]Ratnesar-shumate, S.; Williams, G.; Green, B.; Krause, M.; Holland, B.; Wood, S.; Bohannon, J.; Boydston, J.; Freeburger, D.; Hooper, I.; Beck, K.; Yeager, J.; Altamura, L. A.; Biryukov, J.; Yolitz, J.; Schuit, M.; Wahl, V.; Hevey, M.; Dabisch, P. Simulated Sunlight Rapidly Inactivates SARS-CoV-2 on Surfaces. J. Infect. Dis. 2020, 222 (2), 214–222.Google Scholar https://sci-hub.st/https://doi.org/10.1093/infdis/jiaa274
the first and most important reason is manufacturers have and will optimize for the main benefit of a product. the main product here is light. heat came as a negative byproduct of traditional incandescent lights and heat is something to minimize to lengthen the life of an led bulb.
another possibility is that if it were widespread it could cause some negative outcomes of people sitting too closely to a source of it and potentially exposing the companies to legal issues. not a lawyer and they might be able to shield themselves from that liability with well written disclaimers though.
Along with inertia from the incandescent bulbs not emitting that wavelength... the most likely reason is that they don't want to spend the money on researching how safe it is and how to cost effectively make them like that though.
Normal indoor plants have no need for UV at all. Nor do most food plants -- greenhouse glass blocks UV, for instance.
I think we should figure out how to substitute their influence on humans before we conclude that exposing ourselves to bacteria and viruses a lot is a good thing.
I know I have fixtures that used to have CFLs in them, and any plastic is yellowed significantly.
Some phosphor coatings might be better than others, but they will all leak a certain amount of UV.
There's some misinformation that claims to "kill COVID" (which is a symptom not a virus) so therefore the recommendation is to say "deactivates SARS-COV-2".
Personally I've been trying to reach out to people with scanning electron microscopes, because there's a hypothesis that I'd like to test.
VisualCapitalist have an infographic showing the size of particles, including coronaviruses as 0.1-0.5 microns. I'd assumed a Gaussian bell curve centred around 0.3 micron, but was kindly corrected here on HN that SARS-COV-2 is closer to 0.1 micron.
My hypothesis is that UV-C light at 300 nm = 0.3 micron, or 100 nm = 0.1 micron, will cause the particles to resonate.
In a less formal way, play them the right beat and make the virus dance itself to pieces.
To that end, I bought some UV-C lamps (safely inside plastic boxes) from an aquarium shop. Air filters are all sold out in New Zealand, and suppliers are on holiday. The seller understood, but warned that it can cause sunburn within seconds, and eye damage - so don't look into the blue light! This makes sense because of the size of rod cells in the eye.
Then I got a regular PC fan, and ran it overnight, blowing air through the light. It felt like the air became very dry, and increasingly unpleasant.
Although it didn't smell "fresh", and the window was open for some ventilation, I'm a little worried about ozone production. Not sure how to test that though.
Fabric filters in HVAC will work according to their feature size (like an N95 vs surgical mask), but the difficulty is remembering to change them. So personally I still think UV-C is the solution, I just don't know how to use it safely yet. Certainly it makes sense for disinfecting the mask recycling bins (biohazard infectious substances taken out of the environment = litter picked up) but for ambient air, I'm still learning how to do that safely.
Heck, you can even get filters that greatly exceed the filtration capacity of HEPA filters, and get objects down to .01 microns, which is a tenth to a thirtieth of the size you’re projecting for the smaller particles.
But they are expensive. If you’re interested, look at the IQAir brand.
They are saying the light waves can't penetrate the fist layer of skin... which presumably includes the first layer of eye-ball skin. If true, there shouldn't be any impact to the cornea over time
Chronic exposure to 240nm light causes keratopathies. 222nm is not 240nm of course but I would demand a better study before I agreed to 40+ hours a week of exposure to far-UVC.
https://media.springernature.com/full/springer-static/image/...
Really a great channel, some of the best microphotography out there.
1) How do you deal with the toxic ozone gas that's produced, and
2) How do you prevent eye damage from happening when you look at the device?
Without reading their previous reference, this doesn't make sense. If it doesn't reach the outer layers, what’s blocking the light?
Also, I seriously doubt this wont cause cataracts in the long term.
By Wiki, light < 200 nm is absorbed by O2. The light proposed by the authors is 207< \lambda < 222, so about as energetic as UV can be and not be blocked by the atmosphere. Ill take their word that it cant make it past the layer of dead skin.
But what protects the cornea? Just the very thin layer of tears?
Turn up the HVAC air exchange rate please! There are many other benefits to that.
It's like a recipe for "We can't ever improve anything unless, somehow, magically, there's already common knowledge of the fix." The object-level talk is necessary to getting to common knowledge!
1. Somebody comes with a potentially awesome idea, you have a gut feeling it's risky, and start looking for confirmations of your gut feeling. Way to #hit on somebody else's initiative.
2. "The virus" (we all know we aren't talking about tuberculosis here) is airborne, which means it'll float around. If there are shadows it's not "over", it what scenario it would even mean anything for shadows to be game over? An instantaneous flash once?
3. An alternative is not an argument. Hepa filters work, and I completely agree that we should be using them a lot more but:
3.1 We aren't using them a lot more, so for some reason they don't fix the problem, so alternate solutions are very welcome
3.2 There's room for more than one took in a toolkit, for reasons too obvious to get into.
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Now why am I taking the time to write a comment 5x the length of yours? Because you're merely doing in a somewhat more obvious and inexperienced way what society has been doing for... at least a couple dozen years. Anything new is risky, we should carefully study side effects and only when it's clear there aren't any we're allowed to move forward. This is especially true for medical tech, but it's part of a larger disease that's in the same constellation with NIMBY, regulatory capture and taxi medallions being worth a million.
Covid made it obvious that a lot of emperors didn't wear clothes. We could have had mRNA vaccines quite a bit earlier - and I'm sure the companies involved would have been perfectly happy to make money from them. But no, there had to be a pandemic for regulatory agencies to even consider approving such new tech.
We could have had WFH ten years ago, the tech was here. It took barely weeks for IT departments and worflows to adapt. But no, managers had to negotiate in the strictest terms for even one day a week of WFH, because it's Something That Is Not Done.
And you have a gut feeling that it's risky tech, and I get triggered.
That’s nonsense. There were no regulatory agencies blocking mRNA vaccines. There has been a path towards their approval for a long time. And products such as EndeavorRx, a therapy delivered as a video game, show that FDA is willing to create paths for novel types of therapies in recent years.
QED
People who are dismissive of new ideas based on safety grounds don't need to provide reasoning or evidence or even a coherent argument, they provide a useful function nonetheless by adding friction, forcing inventors to prove that their invention is safe beyond doubt. Since this idea proposes using ionizing radiation around people, a strong dose of scepticism is warranted.
But you made a long comment so I will take the time to engage with you.
1. a potential awesome idea it isnt. Uvc is very strong and every layman should now that it can kill bacteria and viruses … it can even split chemical bonds. And a it should be known that it creates ozon and could cause cancer. But this is a question of the intensity. And also as the ozon layer filters uvc we dont have much contact. But it is safe to asume that if UVA and UVB are causing cancer so should UVC … the next lvl of higher energy is X-ray and gamma and beta. Funny stuff
2. a scenario where to people are talking to each other and the uv cant radiate between them.
3 I did propose the hepa filter because the problem is the following. You have a rate of virus getting in the air and a rate it is killed by uv light and a rate of it is absorbed by the hepa filter. So imho a room were air can circulate easily there should be a possibility of getting to the rate that the air in the room is changed sufficent quickly to not get anough virus to make people ill. UV light is a good choice and allready used in hospitals and cheap. But when nobody is there. But i still dont think its a good idea to throw high energy radiation onto people just to be safe.
3.1 they are expensiv and getting to a solution is not what this society is made for
3.2 i totaly agree with you and every option should be validated.
But do I have the right to an opinion? I dont want to disrupt the discussion about potentialy helping ideas. But when someone stats a doubt it would be nice to answer polite and engaging on the doubt.
And I understand you have a history that made you get triggered but dude … I am not part of that history. Wish you the best
Edit: ar last i want to state that the succes of a medicine to finish phase three is like 1-5% … so good that we have those mechanics to prevent harm to society… but this is a old discusion
But look at the other comments. Look at what zarzavat is saying below. "The burden is on the inventor" - and since he mentions microplastics, I'm allowed to assume he's talking about high levels of certainty and second order effects.
This has never been true in the whole human history. Ever.
This itself, this "being certain every innovation is 100% harmless" is a huge departure from how things have been done, and in itself has a huge risk. I'm not talking about not having shiny new cool stuff, or not having a colony on Mars. I'm talking about apples and apples - about this kind of meta-strategies just plain costing more lives than they save. Google "FDA delenda est", for smarter people than me saying that FDA was way too conservative in the pandemic.
Somebody said below that I'm mistaken about regulatory agencies delaying mRNA before the pandemic. We could of course try and get into the gritty details about what they delayed and why, but just consider one thing: Moderna had their covid vaccine ready in a matter of WEEKS. And it's the same vaccine we're using now. I don't know without googling when Pfizer had their first version, but I imagine it's around the same timeframe. Does this sound like immature technology? When two companies immediately come up with a vaccine when really needed?
What is more likely, that it somehow happened right now for god knows what reason, or that they were both ready to use mRNA but couldn't?
And people keep dying around us. Of Covid, of cancer, of dozen of diseases, not to mention plain old age. This is not about micro-plastics - it's lives vs lives. We have (all around the world) a much more conservative system than we need.
Honestly this question is puzzling me since a while and I cant even state a direction I would take because its to complex for me….. but gut feeling says more transparancy and less complexity could work in designated areas… but … gut feeling.
And as said I understand your first rage. With the past years we are all on the edge with strangers, me too. And I did somehow mumble a bit …
Edit: to the vaccine part. It seems easy to develop them. A friend working at a well known biotech lab was even thinking about making one on the fast way for himself. The hard part is to scale the production and have a good one. As far as I remember those two werent the only ones… but those that worked well. But at first I was rly impressed that they got it that fast and then I was even more impressed about the scalling problem. My friend told me about it and it was fascinating.
Problem is we don't do cost-benefit anymore. With Covid, pretty much any measure they approve becomes very soon mandatory. Vaccines approved for children? Vaccines are now mandatory for children (or strongly encouraged, depending on country).
That's... I don't even know how to call it. Bureaucratic thinking? A properly medical approach would be to have a bunch of tools with various degrees of risk and use them as needed. It's ok if individual doctors have to make more complex decisions. It's ok if guidelines are longer than one page.
Currently they seem to avoid allowing anything more complex than can be explained on TV.
We're looking to ship out units within the next month, here is where you can learn more (https://www.uvxinc.com). I'd love to hear your thoughts/feedback!